The present invention relates to methods for treating certain obsessive compulsive disorders. In particular, the present invention includes methods for treating various repetitive and/or injurious motor activity symptoms of certain obsessive compulsive disorders by peripheral administration of a Clostridial toxin.
Obsessions are persistent ideas, thoughts, impulses or mental images that cause distress and anxiety. Obsessions can involve themes of aggression, contamination, sex or somatic concerns. Compulsions are repetitive, stereotyped motor acts an individual feels required to perform to reduce anxiety or distress. The compulsion usually can be resisted only temporarily, with resistance followed by an increasing sense of unease and tension. The mounting tension is released only by performing the irrational motor act or ritual. Compulsions very in complexity from simple actions such as touching, lip licking, tapping and rubbing to complex behaviors such as repetitive hand washing, hair pulling and body rocking. Additionally, compulsive behaviors can include hoarding, repeating, checking (i.e. repeated checking that a door is locked), counting (i.e. compulsive counting of footsteps) and arranging behaviors, as well as various self-injurious behaviors, such as self-biting (i.e. finger biting), head banging, eye poking, skin picking, skin cutting, skin burning, eye enucleation and castration. Unfortunates with such disturbing self-injurious compulsions must frequently be restrained or fitted with suitable restraints (such as a mouth guard) to prevent further injury to themselves. These compulsions can be severely disabling and can accompany psychosis, intoxication, Tourette's syndrome and mental retardation.
Thus, obsessive compulsive disorders can combine both obsessive thoughts and compulsive behaviors, and can be defined as a chronic condition characterized by recurrent intrusive thoughts and ritualistic behaviors that consume much of the afflicted person's attention and activity, thereby impairing everyday functioning. The behaviors of an obsessive and/or compulsive disorder typically begin in late childhood or early adulthood and the patient experiences marked tension and distress upon resisting the obsessions and compulsions. Epidemiologic data indicates a lifetime prevalence of 2 to 3 percent worldwide and obsessive compulsive disorders are more common in males and in first born children. See e.g. page 2490 of Fauci, A. S. et al., editors, Harrison's Principles of Internal Medicine, McGraw Hill, fourteenth edition (1998).
Functional neuroimaging (i.e. positron emission tomography) studies, brain lesion analysis, and the results of neurosurgical intervention to treat obsessive compulsive disorders indicate that dysfunction within particular basal ganglia and ventral prefrontal cortical structures provides a proposed pathophysiology for obsessive compulsive disorders. See e.g. pages 963-964 of Zigmond, M. J. et al, editors, Fundamental Neuroscience, Academic Press (1999).
Clearly, obsessive compulsive disorders can cause great embarrassment, distress and anguish to both the cognizant patient so afflicted as well as to his or her caregiver.
Tourette's Syndrome
Tourette's syndrome is usually characterized by multiple motor tics and one or more vocal tics. The tics can appear simultaneously or at different periods during the illness. The tics can occur many times a day, and recurrently throughout a period of more than one year. During this period, there is almost never a tic-free period of more than a few consecutive months. Those afflicted with Tourette's syndrome suffer disturbances which can comprise complex tics and cause marked distress or significant impairment in social, occupational, and other important areas of functioning. The onset of the disorder is typically before the age of eighteen. The complex tics of Tourette's syndrome are not due to the direct physiological effects of a substance (e.g., stimulants) or a general medical condition (e.g., Huntington's disease or postviral encephalitis) and are thought to be a part of the Tourette's disease process. The anatomical location, number, frequency, complexity, and severity of the tics often change over time. The tics typically involve the head and, frequently, other parts of the body, such as the torso and upper and lower limbs. The vocal tics include various words or sounds such as clicks, grunts, yelps, barks, sniffs, snorts, and coughs. Coprolalia (a complex vocal tic involving the uttering of obscenities), is present in a few individuals (less than 10%) with this disorder. Complex motor tics involving touching, squatting, deep knee bends, retracing steps, and twirling when walking may be present. In approximately one-half the individuals with this disorder. The first symptoms to appear are often bouts of a single tic, most frequently eye blinking, less frequently tics involving another part of the face or the body. Initial symptoms can also include tongue protrusion, squatting, sniffing, hopping, skipping, throat clearing, stuttering, uttering sounds or words, and coprolalia.
Whereas the repetitive motor activities symptomatic of Tourette's syndrome can be characterized as true tics (that is, as habitual, repeated contraction of certain muscles, as in throat clearing, sniffing, lip pursing or excessive blinking) they are an isolated and distinct subset of behaviors distinct from obsessive compulsive disorders, as defined by the Diagnostic and Statistical Manual of the American Psychiatric Association (the “DSM-IVR”, fourth revised edition). There are a number of obsessive and/or compulsive disorders which involve more complex non tic repetitive motor activity, frequently injurious, as can occur in dermatillomania, trichotillomania, hand washing, head banging, eye poking, body rocking, finger biting, counting, and checking disorders.
Dermatillomania (Compulsive Skin Picking)
The primary characteristic of compulsive skin picking is the repetitive picking at one's own skin to the extent of causing damage. Usually, but not always, the face is the primary location for skin picking. However compulsive skin picking, also known as dermatillomania or neurotic excoriation, can involve any part of the body. Individuals with compulsive skin picking may pick at normal skin variations such as freckles and moles, at actual pre-existing scabs, sores or acne blemishes, or at imagined skin defects that nobody else can observe. The compulsive skin picking patient may use his or her fingernails, as well as their teeth, tweezers, pins or other mechanical devices. As a result, dermatillomania can cause bleeding, bruises, infections, and/or permanent disfigurement of the skin.
Sometimes skin-picking is preceded by a high level of tension and a strong itch or urge to pick. Likewise, carrying out the skin-picking can be followed by a feeling of relief or pleasure. A compulsive skin picking episode can be a conscious response to anxiety or depression, but is frequently done as an unconscious habit. Individuals with compulsive skin picking often attempt to camouflage the damage caused to their skin by using make-up or wearing clothes to cover the subsequent marks and scars. In extreme cases, individuals with compulsive skin picking avoid social situations in an effort to prevent others from seeing the scars, scabs, and bruises that result from skin picking.
The primary treatment modality for compulsive skin picking depends on the level of awareness the individual has regarding the problem. If the compulsive skin picking is generally an unconscious habit, the primary treatment is a form of cognitive-behavioral therapy called habit reversal training (HRT). HRT is based on the principle that skin-picking is a conditioned response to specific situations and events, and that the individual with compulsive skin picking is frequently unaware of these triggers. HRT challenges the problem in a two-fold process. First, the individual with compulsive skin picking learns how to become more consciously aware of situations and events that trigger skin-picking episodes. Second, the individual learns to utilize alternative behaviors in response to these situations and events. Unfortunately HRT does not have a high success rate. If the patient is unaware of or not fully cognizant of his compulsive skin picking, pharmacologic therapy is recommended. Significant side effects have occurred from the current drug therapy.
Trichotillomania (Compulsive Hair Pulling)
Trichotillomania (TTM) is an compulsive disorder where the patient pulls out his or her hair from the scalp, eyelashes, eyebrows, or other parts of the body, resulting in noticeable bald patches. Thus symptoms of trichotillomania includes recurrent pulling out of one's hair resulting in noticeable hair loss, and this is usually preceded by an increasing sense of tension immediately before pulling out the hair or when resisting the behavior, followed by pleasure, gratification, or relief while the hair is being pulled out. This disorder can cause significant distress and impairment in social, occupational, or other important areas of functioning. It is estimated that trichotillomania affects one to two percent of the population, or four to eleven million Americans. TTM seems to strike most frequently in the pre-or early adolescent years. The typical first-time hair puller is 12 years old, although TTM has affected people as young as one and as old as seventy. About ninety percent of those with TTM are women.
Although the symptoms range greatly in severity, location on the body, and response to treatment, most people with TTM pull enough hair over a long enough period of time that they have bald spots on their heads (or missing eyelashes, eyebrows, pubic, or underarm hair), which they go to great lengths to cover with hairstyles, scarves or clothing, or makeup. The persistence of the compulsion can vary considerably, at times, the urge may be so strong that it makes thinking of anything else nearly impossible.
Treatments for TTM include behavioral therapy and drugs. In behavioral therapy, patients learn a structured method of keeping track of the symptoms and associated behaviors, increasing awareness of pulling, substituting incompatible behaviors and several other techniques aimed at reversing the “habit” of pulling. Although medications clearly help some people temporarily, symptoms are likely to return when the medication is stopped unless behavioral therapy is incorporated into treatment. Medications may help to reduce the depression and any obsessive-compulsive symptoms the person may be experiencing. Commonly used medications include fluoxetine (Prozac), fluvoxamine (Luvox), sertraline (Zoloft), paroxetine (Paxil), clomipramine (Anafranil), valproate (Depakote), and lithium carbonate (Lithobid, Eskalith). Unfortunately, behavioral therapies have limited success, and the drugs therapies can have significant side effects and require regular, chronic repeat dosings.
Thus, there are many drawbacks and deficiencies with current obsessive compulsive disorder therapies. Treatment regimes available include chronic administration of drugs which inhibit serotonin reuptake (such drugs are called SSRIs or serotonin reuptake inhibitors) and behavior modification therapies. Clomipramine, fluoxetine and fluvoxamine are approved for the treatment of obsessive compulsive disorders. Notably, clomipramine is a tricyclic antidepressant which is poorly tolerated due to significant anticholinergic and sedative side effects. Additionally, fluoxetine and fluvoxamine (SSRIs) also have a side effect profile, which can include cardiac arrhythmias, although they tend to be more benign that clomipramine. Furthermore, only about 50 to 60 percent of patients with an obsessive compulsive disorder show an acceptable degree of improvement when either or both pharmacotherapies, and behavior modification strategies have been tried.
Botulinum Toxin
The genus Clostridium has more than one hundred and twenty seven species, grouped according to their morphology and functions. The anaerobic, gram positive bacterium Clostridium botulinum produces a potent polypeptide neurotoxin, botulinum toxin, which causes a neuroparalytic illness in humans and animals referred to as botulism. The spores of Clostridium botulinum are found in soil and can grow in improperly sterilized and sealed food containers of home based canneries, which are the cause of many of the cases of botulism. The effects of botulism typically appear 18 to 36 hours after eating the foodstuffs infected with a Clostridium botulinum culture or spores. The botulinum toxin can apparently pass unattenuated through the lining of the gut and attack peripheral motor neurons. Symptoms of botulinum toxin intoxication can progress from difficulty walking, swallowing, and speaking to paralysis of the respiratory muscles and death.
Botulinum toxin type A is the most lethal natural biological agent known to man. About 50 picograms of a commercially available botulinum toxin type A (purified neurotoxin complex)1 is a LD50 in mice (i.e. 1 unit). One unit of BOTOX® contains about 50 picograms (about 56 attomoles) of botulinum toxin type A complex. Interestingly, on a molar basis, botulinum toxin type A is about 1.8 billion times more lethal than diphtheria, about 600 million times more lethal than sodium cyanide, about 30 million times more lethal than cobra toxin and about 12 million times more lethal than cholera. Singh, Critical Aspects of Bacterial Protein Toxins, pages 63-84 (chapter 4) of Natural Toxins II, edited by B. R. Singh et al., Plenum Press, New York (1976) (where the stated LD50 of botulinum toxin type A of 0.3 ng equals 1 U is corrected for the fact that about 0.05 ng of BOTOX® equals 1 unit). One unit (U) of botulinum toxin is defined as the LD50 upon intraperitoneal injection into female Swiss Webster mice weighing 18 to 20 grams each.
Seven generally immunologically distinct botulinum neurotoxins have been characterized, these being respectively botulinum neurotoxin serotypes A, B, C1, D, E, F and G each of which is distinguished by neutralization with type-specific antibodies. The different serotypes of botulinum toxin vary in the animal species that they affect and in the severity and duration of the paralysis they evoke. For example, it has been determined that botulinum toxin type A is 500 times more potent, as measured by the rate of paralysis produced in the rat, than is botulinum toxin type B. Additionally, botulinum toxin type B has been determined to be non-toxic in primates at a dose of 480 U/kg which is about 12 times the primate LD50 for botulinum toxin type A. Moyer E et al., Botulinum Toxin Type B: Experimental and Clinical Experience, being chapter 6, pages 71-85 of “Therapy With Botulinum Toxin”, edited by Jankovic, J. et al. (1994), Marcel Dekker, Inc. Botulinum toxin apparently binds with high affinity to cholinergic motor neurons, is translocated into the neuron and blocks the release of acetylcholine. Additional uptake can take place through low affinity receptors, as well as by phagocytosis and pinocytosis.
Regardless of serotype, the molecular mechanism of toxin intoxication appears to be similar and to involve at least three steps or stages. In the first step of the process, the toxin binds to the presynaptic membrane of the target neuron through a specific interaction between the heavy chain, H chain, and a cell surface receptor; the receptor is thought to be different for each type of botulinum toxin and for tetanus toxin. The carboxyl end segment of the H chain, Hc, appears to be important for targeting of the toxin to the cell surface.
In the second step, the toxin crosses the plasma membrane of the poisoned cell. The toxin is first engulfed by the cell through receptor-mediated endocytosis, and an endosome containing the toxin is formed. The toxin then escapes the endosome into the cytoplasm of the cell. This step is thought to be mediated by the amino end segment of the H chain, HN, which triggers a conformational change of the toxin in response to a pH of about 5.5 or lower. Endosomes are known to possess a proton pump which decreases intra-endosomal pH. The conformational shift exposes hydrophobic residues in the toxin, which permits the toxin to embed itself in the endosomal membrane. The toxin (or at a minimum the light chain) then translocates through the endosomal membrane into the cytoplasm.
The last step of the mechanism of botulinum toxin activity appears to involve reduction of the disulfide bond joining the heavy chain, H chain, and the light chain, L chain. The entire toxic activity of botulinum and tetanus toxins is contained in the L chain of the holotoxin; the L chain is a zinc (Zn++) endopeptidase which selectively cleaves proteins essential for recognition and docking of neurotransmitter-containing vesicles with the cytoplasmic surface of the plasma membrane, and fusion of the vesicles with the plasma membrane. Tetanus neurotoxin, botulinum toxin types B, D, F, and G cause degradation of synaptobrevin (also called vesicle-associated membrane protein (VAMP)), a synaptosomal membrane protein. Most of the VAMP present at the cytoplasmic surface of the synaptic vesicle is removed as a result of any one of these cleavage events. Botulinum toxin serotype A and E cleave SNAP-25. Botulinum toxin serotype C1 was originally thought to cleave syntaxin, but was found to cleave syntaxin and SNAP-25. Each of the botulinum toxins specifically cleaves a different bond, except botulinum toxin type B (and tetanus toxin) which cleave the same bond. Each of these cleavages block the process of vesicle-membrane docking, thereby preventing exocytosis of vesicle content.
Botulinum toxins have been used in clinical settings for the treatment of neuromuscular disorders characterized by hyperactive skeletal muscles (i.e. motor disorders). In 1989 a botulinum toxin type A complex has been approved by the U.S. Food and Drug Administration for the treatment of blepharospasm, strabismus and hemifacial spasm. Subsequently, a botulinum toxin type A was also approved by the FDA for the treatment of cervical dystonia and for the treatment of glabellar lines, and a botulinum toxin type B was approved for the treatment of cervical dystonia. Non-type A botulinum toxin serotypes apparently have a lower potency and/or a shorter duration of activity as compared to botulinum toxin type A. Clinical effects of peripheral intramuscular botulinum toxin type A are usually seen within one week of injection. The typical duration of symptomatic relief from a single intramuscular injection of botulinum toxin type A averages about three months, although significantly longer periods of therapeutic activity have been reported.
Although all the botulinum toxins serotypes apparently inhibit release of the neurotransmitter acetylcholine at the neuromuscular junction, they do so by affecting different neurosecretory proteins and/or cleaving these proteins at different sites. For example, botulinum types A and E both cleave the 25 kiloDalton (kD) synaptosomal associated protein (SNAP-25), but they target different amino acid sequences within this protein. Botulinum toxin types B, D, F and G act on vesicle-associated protein (VAMP, also called synaptobrevin), with each serotype cleaving the protein at a different site. Finally, botulinum toxin type C1 has been shown to cleave both syntaxin and SNAP-25. These differences in mechanism of action may affect the relative potency and/or duration of action of the various botulinum toxin serotypes. Apparently, a substrate for a botulinum toxin can be found in a variety of different cell types. See e.g. Biochem J 1;339 (pt 1):159-65:1999, and Mov Disord, 10(3):376:1995 (pancreatic islet B cells contains at least SNAP-25 and synaptobrevin).
The molecular weight of the botulinum toxin protein molecule, for all seven of the known botulinum toxin serotypes, is about 150 kD. Interestingly, the botulinum toxins are released by Clostridial bacterium as complexes comprising the 150 kD botulinum toxin protein molecule along with associated non-toxin proteins. Thus, the botulinum toxin type A complex can be produced by Clostridial bacterium as 900 kD, 500 kD and 300 kD forms. Botulinum toxin types B and C1 is apparently produced as only a 700 kD or 500 kD complex. Botulinum toxin type D is produced as both 300 kD and 500 kD complexes. Finally, botulinum toxin types E and F are produced as only approximately 300 kD complexes. The complexes (i.e. molecular weight greater than about 150 kD) are believed to contain a non-toxin hemaglutinin protein and a non-toxin and non-toxic nonhemaglutinin protein. These two non-toxin proteins (which along with the botulinum toxin molecule comprise the relevant neurotoxin complex) may act to provide stability against denaturation to the botulinum toxin molecule and protection against digestive acids when toxin is ingested. Additionally, it is possible that the larger (greater than about 150 kD molecular weight) botulinum toxin complexes may result in a slower rate of diffusion of the botulinum toxin away from a site of intramuscular injection of a botulinum toxin complex.
In vitro studies have indicated that botulinum toxin inhibits potassium cation induced release of both acetylcholine and norepinephrine from primary cell cultures of brainstem tissue. Additionally, it has been reported that botulinum toxin inhibits the evoked release of both glycine and glutamate in primary cultures of spinal cord neurons and that in brain synaptosome preparations botulinum toxin inhibits the release of each of the neurotransmitters acetylcholine, dopamine, norepinephrine (Habermann E., et al., Tetanus Toxin and Botulinum A and C Neurotoxins Inhibit Noradrenaline Release From Cultured Mouse Brain, J Neurochem 51(2);522-527:1988) CGRP, substance P and glutamate (Sanchez-Prieto, J., et al., Botulinum Toxin A Blocks Glutamate Exocytosis From Guinea Pig Cerebral Cortical Synaptosomes, Eur J. Biochem 165;675-681:1897. Thus, when adequate concentrations are used, stimulus-evoked release of most neurotransmitters is blocked by botulinum toxin. See e.g. Pearce, L. B., Pharmacologic Characterization of Botulinum Toxin For Basic Science and Medicine, Toxicon 35(9);1373-1412 at 1393; Bigalke H., et al., Botulinum A Neurotoxin Inhibits Non-Cholinergic Synaptic Transmission in Mouse Spinal Cord Neurons in Culture, Brain Research 360;318-324:1985; Habermann E., Inhibition by Tetanus and Botulinum A Toxin of the release of [3H]Noradrenaline and [3H]GABA From Rat Brain Homogenate, Experientia 44;224-226:1988, Bigalke H., et al., Tetanus Toxin and Botulinum A Toxin Inhibit Release and Uptake of Various Transmitters, as Studied with Particulate Preparations From Rat Brain and Spinal Cord, Naunyn-Schmiedeberg's Arch Pharmacol 316;244-251:1981, and; Jankovic J. et al., Therapy With Botulinum Toxin, Marcel Dekker, Inc., (1994), page 5.
Botulinum toxin type A can be obtained by establishing and growing cultures of Clostridium botulinum in a fermenter and then harvesting and purifying the fermented mixture in accordance with known procedures. All the botulinum toxin serotypes are initially synthesized as inactive single chain proteins which must be cleaved or nicked by proteases to become neuroactive. The bacterial strains that make botulinum toxin serotypes A and G possess endogenous proteases and serotypes A and G can therefore be recovered from bacterial cultures in predominantly their active form. In contrast, botulinum toxin serotypes C1, D and E are synthesized by nonproteolytic strains and are therefore typically unactivated when recovered from culture. Serotypes B and F are produced by both proteolytic and nonproteolytic strains and therefore can be recovered in either the active or inactive form. However, even the proteolytic strains that produce, for example, the botulinum toxin type B serotype only cleave a portion of the toxin produced. The exact proportion of nicked to unnicked molecules depends on the length of incubation and the temperature of the culture. Therefore, a certain percentage of any preparation of, for example, the botulinum toxin type B toxin is likely to be inactive, possibly accounting for the known significantly lower potency of botulinum toxin type B as compared to botulinum toxin type A. The presence of inactive botulinum toxin molecules in a clinical preparation will contribute to the overall protein load of the preparation, which has been linked to increased antigenicity, without contributing to its clinical efficacy. Additionally, it is known that botulinum toxin type B has, upon intramuscular injection, a shorter duration of activity and is also less potent than botulinum toxin type A at the same dose level.
High quality crystalline botulinum toxin type A can be produced from the Hall A strain of Clostridium botulinum with characteristics of ≧3×107 U/mg, an A260/A278 of less than 0.60 and a distinct pattern of banding on gel electrophoresis. The known Schantz process can be used to obtain crystalline botulinum toxin type A, as set forth in Schantz, E. J., et al, Properties and use of Botulinum toxin and Other Microbial Neurotoxins in Medicine, Microbiol Rev. 56;80-99:1992. Generally, the botulinum toxin type A complex can be isolated and purified from an anaerobic fermentation by cultivating Clostridium botulinum type A in a suitable medium. The known process can also be used, upon separation out of the non-toxin proteins, to obtain pure botulinum toxins, such as for example: purified botulinum toxin type A with an approximately 150 kD molecular weight with a specific potency of 1-2×108 LD50 U/mg or greater; purified botulinum toxin type B with an approximately 156 kD molecular weight with a specific potency of 1-2×108 LD50 U/mg or greater, and; purified botulinum toxin type F with an approximately 155 kD molecular weight with a specific potency of 1-2×107 LD50 U/mg or greater.
Botulinum toxins and/or botulinum toxin complexes can be obtained from List Biological Laboratories, Inc., Campbell, Calif.; the Centre for Applied Microbiology and Research, Porton Down, U.K.; Wako (Osaka, Japan), Metabiologics (Madison, Wis.) as well as from Sigma Chemicals of St Louis, Mo. Pure botulinum toxin can also be used to prepare a pharmaceutical composition.
As with enzymes generally, the biological activities of the botulinum toxins (which are intracellular peptidases) is dependant, at least in part, upon their three dimensional conformation. Thus, botulinum toxin type A is detoxified by heat, various chemicals surface stretching and surface drying. Additionally, it is known that dilution of the toxin complex obtained by the known culturing, fermentation and purification to the much, much lower toxin concentrations used for pharmaceutical composition formulation results in rapid detoxification of the toxin unless a suitable stabilizing agent is present. Dilution of the toxin from milligram quantities to a solution containing nanograms per milliliter presents significant difficulties because of the rapid loss of specific toxicity upon such great dilution. Since the toxin may be used months or years after the toxin containing pharmaceutical composition is formulated, the toxin can stabilized with a stabilizing agent such as albumin and gelatin.
A commercially available botulinum toxin containing pharmaceutical composition is sold under the trademark BOTOX® (available from Allergan, Inc., of Irvine, Calif.). BOTOX® consists of a purified botulinum toxin type A complex, albumin and sodium chloride packaged in sterile, vacuum-dried form. The botulinum toxin type A is made from a culture of the Hall strain of Clostridium botulinum grown in a medium containing N-Z amine and yeast extract. The botulinum toxin type A complex is purified from the culture solution by a series of acid precipitations to a crystalline complex consisting of the active high molecular weight toxin protein and an associated hemagglutinin protein. The crystalline complex is re-dissolved in a solution containing saline and albumin and sterile filtered (0.2 microns) prior to vacuum-drying. The vacuum-dried product is stored in a freezer at or below −5° C. BOTOX® can be reconstituted with sterile, non-preserved saline prior to intramuscular injection. Each vial of BOTOX® contains about 100 units (U) of Clostridium botulinum toxin type A purified neurotoxin complex, 0.5 milligrams of human serum albumin and 0.9 milligrams of sodium chloride in a sterile, vacuum-dried form without a preservative.
To reconstitute vacuum-dried BOTOX®, sterile normal saline without a preservative; (0.9% Sodium Chloride Injection) is used by drawing up the proper amount of diluent in the appropriate size syringe. Since BOTOX® may be denatured by bubbling or similar violent agitation, the diluent is gently injected into the vial. For sterility reasons BOTOX® is preferably administered within four hours after the vial is removed from the freezer and reconstituted. During these four hours, reconstituted BOTOX® can be stored in a refrigerator at about 2° C. to about 8° C. Reconstituted, refrigerated BOTOX® has been reported to retain its potency for at least about two weeks. Neurology, 48:249-53:1997.
It has been reported that botulinum toxin type A has been used in clinical settings as follows:    (1) about 75-125 units of BOTOX® per intramuscular injection (multiple muscles) to treat cervical dystonia;    (2) 5-10 units of BOTOX® per intramuscular injection to treat glabellar lines (brow furrows) (5 units injected intramuscularly into the procerus muscle and 10 units injected intramuscularly into each corrugator supercilii muscle);    (3) about 30-80 units of BOTOX® to treat constipation by intrasphincter injection of the puborectalis muscle;    (4) about 1-5 units per muscle of intramuscularly injected BOTOX® to treat blepharospasm by injecting the lateral pre-tarsal orbicularis oculi muscle of the upper lid and the lateral pre-tarsal orbicularis oculi of the lower lid.    (5) to treat strabismus, extraocular muscles have been injected intramuscularly with between about 1-5 units of BOTOX®, the amount injected varying based upon both the size of the muscle to be injected and the extent of muscle paralysis desired (i.e. amount of diopter correction desired).    (6) to treat upper limb spasticity following stroke by intramuscular injections of BOTOX® into five different upper limb flexor muscles, as follows:    (a) flexor digitorum profundus: 7.5 U to 30 U    (b) flexor digitorum sublimus: 7.5 U to 30 U    (c) flexor carpi ulnaris: 10 U to 40 U    (d) flexor carpi radialis: 15 U to 60 U    (e) biceps brachii: 50 U to 200 U. Each of the five indicated muscles has been injected at the same treatment session, so that the patient receives from 90 U to 360 U of upper limb flexor muscle BOTOX® by intramuscular injection at each treatment session.    (7) to treat migraine, pericranial injected (injected symmetrically into glabellar, frontalis and temporalis muscles) injection of 25 U of BOTOX® has showed significant benefit as a prophylactic treatment of migraine compared to vehicle as measured by decreased measures of migraine frequency, maximal severity, associated vomiting and acute medication use over the three month period following the 25 U injection.
Additionally, intramuscular botulinum toxin has been used in the treatment of tremor in patients with Parkinson's disease, although it has been reported that results have not been impressive. Marjama-Lyons, J., et al., Tremor-Predominant Parkinson's Disease, Drugs & Aging 16(4);273-278:2000.
It is known that botulinum toxin type A can have an efficacy for up to 12 months (European J. Neurology 6 (Supp 4): S111-S1150:1999), and in some circumstances for as long as 27 months. The Laryngoscope 109:1344-1346:1999. However, the usual duration of an intramuscular injection of Botox® is typically about 3 to 4 months.
The success of botulinum toxin type A to treat a variety of clinical conditions has led to interest in other botulinum toxin serotypes. Two commercially available botulinum type A preparations for use in humans are BOTOX® available from Allergan, Inc., of Irvine, Calif., and Dysport® available from Beaufour Ipsen, Porton Down, England. A Botulinum toxin type B preparation (MyoBloc®) is available from Elan Pharmaceuticals of San Francisco, Calif.
In addition to having pharmacologic actions at the peripheral location, botulinum toxins may also have inhibitory effects in the central nervous system. Work by Weigand et al, Naunyn-Schmiedeberg's Arch. Pharmacol. 1976; 292, 161-165, and Habermann, Naunyn-Schmiedeberg's Arch. Pharmacol. 1974; 281, 47-56 showed that botulinum toxin is able to ascend to the spinal area by retrograde transport. As such, a botulinum toxin injected at a peripheral location, for example intramuscularly, may be retrograde transported to the spinal cord.
U.S. Pat. No. 5,989,545 discloses that a modified clostridial neurotoxin or fragment thereof, preferably a botulinum toxin, chemically conjugated or recombinantly fused to a particular targeting moiety can be used to treat pain by administration of the agent to the spinal cord.
A botulinum toxin has also been proposed for the treatment of rhinorrhea, hyperhydrosis and other disorders mediated by the autonomic nervous system (U.S. Pat. No. 5,766,605), tension headache, (U.S. Pat. No. 6,458,365), migraine headache (U.S. Pat. No. 5,714,468), post-operative pain and visceral pain (U.S. Pat. No. 6,464,986), pain treatment by intraspinal toxin administration (U.S. Pat. No. 6,113,915), Parkinson's disease and other diseases with a motor disorder component, by intracranial toxin administration (U.S. Pat. No. 6,306,403), hair growth and hair retention (U.S. Pat. No. 6,299,893), psoriasis and dermatitis (U.S. Pat. No. 5,670,484), injured muscles (U.S. Pat. No. 6,423,319, various cancers (U.S. Pat. No. 6,139,845), pancreatic disorders (U.S. Pat. No. 6,143,306), smooth muscle disorders (U.S. Pat. No. 5,437,291, including injection of a botulinum toxin into the upper and lower esophageal, pyloric and anal sphincters)), prostate disorders (U.S. Pat. No. 6,365,164), inflammation, arthritis and gout (U.S. Pat. No. 6,063,768), juvenile cerebral palsy (U.S. Pat. No. 6,395,277), inner ear disorders (U.S. Pat. No. 6,265,379), thyroid disorders (U.S. Pat. No. 6,358,513), parathyroid disorders (U.S. Pat. No. 6,328,977). Additionally, controlled release toxin implants are known (see e.g. U.S. Pat. Nos. 6,306,423 and 6,312,708).
A botulinum toxin has been used to treat recalcitrant restless leg syndrome (Kudelko, K. M., et al., Successful treatment of recalcitrant Restless Legs Syndrome with botulinum toxin A, Mov Disord 2002;17 (Suppl 5):S242). Restless leg syndrome (RLS) involves an uncomfortable sensation in muscles, usually in the legs and thighs that occurs most commonly in middle aged woman. The abnormal sensation is relieved by moving the legs. RLS is not an obsessive compulsive disorder because it is not characterized by either recurrent intrusive thoughts or ritualistic behaviors. The amount of a botulinum toxin administered to treat restless leg syndrome (i.e. 25-50 units of a type A botulinum toxin per leg) exceeds the amount of toxin typically used to reduce the tone of a hypertonic or rigid thigh muscle, and can indeed can cause some paralysis of the injected thigh muscle.
Additionally, the finger biting, lip biting and tongue biting self mutilation behaviors of Lesch Nyhan syndrome have been treated by injecting a botulinum toxin into the chewing or clenching muscles of the mouth in one patient. Dabrowski E., et al, Botulinum toxin as a novel treatment for self-mutilation in Lesch-Nyhan syndrome, Ann Neurol 2002 September; 52 (3 Supp 1): S157. Injection of the fingers, lips or tongue is believed contraindicated because of the ulceration and sensitivity of these extremities due to the injurious behaviors of the syndrome.
Furthermore, a botulinum toxin has been used to treat focal dystonic tics or muscle spasms of Tourette's syndrome. Jankovic, J., Botulinum toxin in the treatment of tics associated with Tourette's syndrome, Neurology 1993 April; 43 (4 Supp 2): A310; Jankovic, J., Botulinum toxin in the treatment of dystonic tics, Mov Disord 1994 May; 9(3): 347-9, and; Krauss J., et al., Severe motor tics causing cervical myelopathy in Tourette's syndrome, Mov Disord 1996; 11(5): 563-6. These publications indicate that a botulinum toxin can act to treat a Tourette's syndrome tic both by reducing the force of contraction necessary to generate the muscle movement (i.e. by a partial paralysis of the tic involved muscles) as well as by an inhibition or resolution of the premonitory symptoms (i.e. by removing the urge to carry out or to accomplish the tic) which precede the tic. Unfortunately, significant neck pain, neck weakness and neck pain was reported in some of the Tourette's syndrome patient's administered a botulinum toxin to treat a neck tic. Additionally, the literature is contradictory with regard to use of a botulinum toxin to treat a Tourette's syndrome tic, as others have reported no relief upon use of botulinum toxin to treat a Tourette syndrome tic, even at dose levels that caused muscle weakness or paralysis. Chappell, P. B., et al., Future therapies of Tourette syndrome, Neurol Clin 1997 May; 15(2): 429-50, at 444.
Tetanus toxin, as well as derivatives (i.e. with a non-native targeting moiety), fragments, hybrids and chimeras thereof can also have therapeutic utility. The tetanus toxin bears many similarities to the botulinum toxins. Thus, both the tetanus toxin and the botulinum toxins are polypeptides made by closely related species of Clostridium (Clostridium tetani and Clostridium botulinum, respectively). Additionally, both the tetanus toxin and the botulinum toxins are dichain proteins composed of a light chain (molecular weight about 50 kD) covalently bound by a single disulfide bond to a heavy chain (molecular weight about 100 kD). Hence, the molecular weight of tetanus toxin and of each of the seven botulinum toxins (non-complexed) is about 150 kD. Furthermore, for both the tetanus toxin and the botulinum toxins, the light chain bears the domain which exhibits intracellular biological (protease) activity, while the heavy chain comprises the receptor binding (immunogenic) and cell membrane translocational domains.
Further, both the tetanus toxin and the botulinum toxins exhibit a high, specific affinity for gangliocide receptors on the surface of presynaptic cholinergic neurons. Receptor mediated endocytosis of tetanus toxin by peripheral cholinergic neurons results in retrograde axonal transport, blocking of the release of inhibitory neurotransmitters from central synapses and a spastic paralysis. Contrarily, receptor mediated endocytosis of botulinum toxin by peripheral cholinergic neurons results in little if any retrograde transport, inhibition of acetylcholine exocytosis from the intoxicated peripheral motor neurons and a flaccid paralysis.
Finally, the tetanus toxin and the botulinum toxins resemble each other in both biosynthesis and molecular architecture. Thus, there is an overall 34% identity between the protein sequences of tetanus toxin and botulinum toxin type A, and a sequence identity as high as 62% for some functional domains. Binz T. et al., The Complete Sequence of Botulinum Neurotoxin Type A and Comparison with Other Clostridial Neurotoxins, J Biological Chemistry 265(16);9153-9158:1990.
Acetylcholine
Typically only a single type of small molecule neurotransmitter is released by each type of neuron in the mammalian nervous system, although there is evidence which suggests that several neuromodulators can be released by the same neuron. The neurotransmitter acetylcholine is secreted by neurons in many areas of the brain, but specifically by the large pyramidal cells of the motor cortex, by several different neurons in the basal ganglia, by the motor neurons that innervate the skeletal muscles, by the preganglionic neurons of the autonomic nervous system (both sympathetic and parasympathetic), by the bag 1 fibers of the muscle spindle fiber, by the postganglionic neurons of the parasympathetic nervous system, and by some of the postganglionic neurons of the sympathetic nervous system. Essentially, only the postganglionic sympathetic nerve fibers to the sweat glands, the piloerector muscles and a few blood vessels are cholinergic as most of the postganglionic neurons of the sympathetic nervous system secret the neurotransmitter norepinephine. In most instances acetylcholine has an excitatory effect. However, acetylcholine is known to have inhibitory effects at some of the peripheral parasympathetic nerve endings, such as inhibition of heart rate by the vagal nerve.
The efferent signals of the autonomic nervous system are transmitted to the body through either the sympathetic nervous system or the parasympathetic nervous system. The preganglionic neurons of the sympathetic nervous system extend from preganglionic sympathetic neuron cell bodies located in the intermediolateral horn of the spinal cord. The preganglionic sympathetic nerve fibers, extending from the cell body, synapse with postganglionic neurons located in either a paravertebral sympathetic ganglion or in a prevertebral ganglion. Since, the preganglionic neurons of both the sympathetic and parasympathetic nervous system are cholinergic, application of acetylcholine to the ganglia will excite both sympathetic and parasympathetic postganglionic neurons.
Acetylcholine activates two types of receptors, muscarinic and nicotinic receptors. The muscarinic receptors are found in all effector cells stimulated by the postganglionic, neurons of the parasympathetic nervous system as well as in those stimulated by the postganglionic cholinergic neurons of the sympathetic nervous system. The nicotinic receptors are found in the adrenal medulla, as well as within the autonomic ganglia, that is on the cell surface of the postganglionic neuron at the synapse between the preganglionic and postganglionic neurons of both the sympathetic and parasympathetic systems. Nicotinic receptors are also found in many nonautonomic nerve endings, for example in the membranes of skeletal muscle fibers at the neuromuscular junction.
Acetylcholine is released from cholinergic neurons when small, clear, intracellular vesicles fuse with the presynaptic neuronal cell membrane. A wide variety of non-neuronal secretory cells, such as, adrenal medulla (as well as the PC12 cell line) and pancreatic islet cells release catecholamines and parathyroid hormon , respectively, from large dense-core vesicles. The PC12 cell line is a clone of rat pheochromocytoma cells extensively used as a tissue culture model for studies of sympathoadrenal development. Botulinum toxin inhibits the release of both types of compounds from both types of cells in vitro, permeabilized (as by electroporation) or by direct injection of the toxin into the denervated cell. Botulinum toxin is also known to block release of the neurotransmitter glutamate from cortical synaptosomes cell cultures.
A neuromuscular junction is formed in skeletal muscle by the proximity of axons to muscle cells. A signal transmitted through the nervous system results in an action potential at the terminal axon, with activation of ion channels and resulting release of the neurotransmitter acetylcholine from intraneuronal synaptic vesicles, for example at the motor endplate of the neuromuscular junction. The acetylcholine crosses the extracellular space to bind with acetylcholine receptor proteins on the surface of the muscle end plate. Once sufficient binding has occurred, an action potential of the muscle cell causes specific membrane ion channel changes, resulting in muscle cell contraction. The acetylcholine is then released from the muscle cells and metabolized by cholinesterases in the extracellular space. The metabolites are recycled back into the terminal axon for reprocessing into further acetylcholine.
What is needed therefore is a non-surgical method for effectively treating effectively treating inappropriate, compulsive, ritualistic and/or obsessive behaviors characterized by repetitive, unproductive motor activity.